Zobrazeno 1 - 10
of 1 550
pro vyhledávání: '"Tomita, A. H."'
We prove that the existence of $\mathfrak{c}$ incomparable selective ultrafilters implies the existence of a Wallace semigroup whose cube is countably compact. In addition, assuming the existence of $2^{\mathfrak c}$ incomparable selective ultrafilte
Externí odkaz:
http://arxiv.org/abs/2210.08688
We prove that if there are $\mathfrak c$ incomparable selective ultrafilters then, for every infinite cardinal $\kappa$ such that $\kappa^\omega=\kappa$, there exists a group topology on the free Abelian group of cardinality $\kappa$ without nontrivi
Externí odkaz:
http://arxiv.org/abs/2103.12917
Publikováno v:
Acta Math. Hungarica 159 414--428 (2019)
We prove that the existence of a selective ultrafilter implies the existence of a countably compact Hausdorff group topology on the free Abelian group of size continuum. As a consequence, we show that the existence of a selective ultrafilter implies
Externí odkaz:
http://arxiv.org/abs/1909.03607
Assuming the existence of $\mathfrak c$ incomparable selective ultrafilters, we classify the non-torsion Abelian groups of cardinality $\mathfrak c$ that admit a countably compact group topology. We show that for each $\kappa \in [\mathfrak c, 2^\mat
Externí odkaz:
http://arxiv.org/abs/1909.03340
Autor:
Bellini, Matheus K. b, 1, Hart, Klaas Pieter a, Rodrigues, Vinicius O. c, d, ⁎, 2, Tomita, Artur H. b, 3
Publikováno v:
In Topology and its Applications 15 June 2023 333
We study the relations between a generalization of pseudocompactness, named $(\kappa, M)$-pseudocompactness, the countably compactness of subspaces of $\beta \omega$ and the pseudocompactness of their hyperspaces. We show, by assuming the existence o
Externí odkaz:
http://arxiv.org/abs/1710.06087
Autor:
Garcia-Ferreira, S., Tomita, A. H.
A space $X$ is called {\it selectively pseudocompact} if for each sequence $(U_{n})_{n\in \mathbb{N}}$ of pairwise disjoint nonempty open subsets of $X$ there is a sequence $(x_{n})_{n\in \mathbb{N}}$ of points in $X$ such that $cl_X(\{x_n : n < \ome
Externí odkaz:
http://arxiv.org/abs/1706.04911
A {\it weak selection} on $\mathbb{R}$ is a function $f: [\mathbb{R}]^2 \to \mathbb{R}$ such that $f(\{x,y\}) \in \{x,y\}$ for each $\{x,y\} \in [\mathbb{R}]^2$. In this article, we continue with the study (which was initiated in \cite{ag}) of the ou
Externí odkaz:
http://arxiv.org/abs/1608.06210
Publikováno v:
Fund. Math. 238 (2017), no. 1, 79-100
A topological group $G$ is said to have a local $\omega^\omega$-base if the neighbourhood system at identity admits a monotone cofinal map from the directed set $\omega^\omega$. In particular, every metrizable group is such, but the class of groups w
Externí odkaz:
http://arxiv.org/abs/1511.07062
Autor:
Cao, Jiling, Tomita, Artur H.
In this paper, we continue the study of function spaces equipped with topologies of (strong) uniform convergence on bornologies initiated by Beer and Levi \cite{beer-levi:09}. In particular, we investigate some topological properties these function s
Externí odkaz:
http://arxiv.org/abs/1403.6905